The present invention relates generally to an optical switching system, and more specifically to a wavelength time division multiplexed optical switching system in which optical signals are multiplexed both in time and wavelength domains to provide switching between time slots and between wavelengths.
A prior art time and wavelength division multiplexed optical switching system described in Japanese Patent Application No. 58-033069 is made up of a first time switching stage, an intermediate, wavelength switching stage and a second time switching stage, with the successive stages being interconnected by optical links. However, the use of two time switching stages requires a substantial amount of optical switching elements. In addition, the time-wavelength-time switching configuration lacks the ability to implement a multistage configuration having a capacity exceeding beyond the capacity of "n.times.m" multiplex.
Another prior art system is a time and wavelength division multiplexed system for transmission of a desired program from a central source to subscriber terminals. This involves the use of a substantial amount of optical components such as wavelength selectors and photodiode arrays and electronic components such as time division selectors and electrooptical converters.